1. Field of the Invention
The present invention relates generally to assembling a vehicle on a continuously moving vehicle assembly line, and more particularly to a performance feedback system for assembling a vehicle on a continuously moving vehicle assembly line.
2. Description of Related Art
In the early days of assembly line automobile production, a method of vehicle assembly accounting was necessary to insure that all of the options on a custom manufactured vehicle were actually assembled. The automotive industry in turn expanded this method of vehicle accounting by recording vehicle defects encountered during manufacturing as well as the necessary repairs done to correct these defects. In those days, this information was recorded on what was called a "traveling ticket", a paper ticket that traveled with the vehicle along the assembly line.
Presently, with the relatively recent advances in computer technology, a different method is used to track and record vehicle assembly data as the vehicle moves along the assembly line. This method is referred to as the Vehicle Assembly Method disclosed in U.S. Pat. No. 4,709,337, issued Nov. 29, 1987, to inventors Knapp et al, the disclosure of which is hereby incorporated by reference.
The patented Vehicle Assembly Method uses a computer record, called a vehicle line tracking record, that travels along the assembly line with each vehicle, replacing the paper ticket. Each vehicle line tracking record contains information referred to as vehicle build data. Vehicle build data contained within the record consists of information such as the vehicle line tracking number (essentially a vehicle ID number), and assembly related information (what options to include, defects reported during assembly, repairs made during assembly, etc.). The vehicle line tracking record is accessed during vehicle assembly by assembly station operators to determine what operations to perform on the vehicle while it is at their station. Further, it is used to report any defects or repairs made to the vehicle during production. The vehicle line tracking record is also accessed at upgrade assembly stations where repairs are made to vehicles with reported defects.
The hardware, for the Vehicle Assembly Method, consists of several Production Data Terminals (PDT's), linked by computer bus line to Junction Boxes which in turn are connected to Plant DCL's (e.g., "data concentrators" or parallel I/O ports). The line of computer communication finally terminates as the Plant DCL feeds into the Host DCL which is connected to a mainframe computer. The PDT's are data entry terminals which are used to record vehicle assembly data. The PDT's consist of twelve buttons or switches, a Change Sequence switch, End of Operation switch and ten numbered switches. The Change Sequence switch is used by the station operators to correct the vehicle line tracking number displayed on the PDT to correspond with the vehicle line tracking number of the unit in their work station. It does so by incrementing the vehicle's line tracking record and number then downloading it into that assembly work station's PDT. The End of Operation switch is pressed by the operator to indicate that he has completed all required assembly operations on the vehicle regardless of whether or not they were successfully performed. Additionally, pressing the End of Operation switch updates the vehicle line tracking record with the newly inputted information. The remaining numbered switches are pressed by the assembly work station operator as necessary to record any manufacturing defect that is noticed during assembly.
However, there are several disadvantages with the above patented Vehicle Assembly Method. At the beginning of a work shift, if an operator does not verify that the vehicle line tracking number displayed on his PDT corresponds to the vehicle line tracking number of the unit in their work station, inputted information will then be attributed to the wrong vehicle's computer line tracking record until a correction is made. Additionally, if the operator fails to press the End of Operation switch, no input will be attributed to the vehicle's computer line tracking record. If the operator later wants to input data against a vehicle he must use the Change Sequence switch to enter the correct vehicle line tracking number or the operator will continue to report defect data against the wrong vehicle. When a vehicle reaches special repair assembly work stations called upgrade stations, the vehicle's line tracking record is displayed on a CRT notifying the upgrade operator of possible defects. If the vehicle line tracking number was incorrect during input from PDT's, defects will be generated against the wrong vehicle. Thus, a vehicle without any defects may show defects which really belong to a different vehicle. Expensive labor time will be wasted searching vehicles with improperly attributed defect warnings. However, a vehicle which should have shown defect warnings may pass inspection and be sold to a consumer, resulting in expensive warranty costs.